Capping means for electric vacuum tubes



July 25, 1950 A. COMMIN CAPPING MEANS FOR ELECTRIC VACUUM TUBES Filed April l5, 1947 INVENTOR.

fiALD/QE comm //V Patented July 25, 1950 UNITED STATES PATENT OFFICE Andre Commin, Paris, France, assignor to Societe Francaise Radio Electnque, a corporation of France Application April 15, 1947, Serial No. 741,654 In France March 27, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires March 27, 1966 4 Claims. (Cl. 250-275) The progress made in the manufacture of radio valves or incandescent lamps is such that it is possible, in certain cases, to make direct use of the current lead-in conductors as pins for the valve or lamp, thereby avoiding the necessity for capping. For this purpose, however, it is necessary for the lead-in conductors to be sufficiently rigid and to be accurately positioned relatively to the support which holds the valve or lamp when in use.

The objects of the invention and the invention itself will be better understood from the following detailed description of some embodiments thereof when read with the accompanying drawings, wherein Figure 1 is a cross sectional view of a valve base showing a partial capping for the exhaust tube,

Figure 2 is a similar view showing a complete ppin Figure 3 is a further similar view, according to the invention, of a cap of insulating material of particular shape, and

Figures 4a and 4b are related views, partly in section, showing a further structural form of the cap.

In cases in which the exhaust tube of the valve or lamp is located in the foot or base, it is still possible to use the direct pinning arrangement but it is then necessary to protect the exhaust tube by means of a partial capping of the base, as shown in Figure 1, which illustrates, in section, part of a lamp L at the level of its base, P designating the current input leads, Q the closed exhaust tube, C the cap surrounding Q, o

and Y a special paste serving to secure the cap to the lamp.

Finally, there are numerous cases in which the current leads are very thin and, consequently, are not rigid enough to be used as pins, so that it becomes necessary to consider capping the completed lamp or valve, independently of or concurrently with the necessity of protecting the exhaust tube. In such cases, as shown diagrammatically, in section, in Figure 2, the cap C, of any material, is secured to the lamp or valve L by means of a special paste Y: the bottom of the cap is formed by a piece of insulating material X from which protrude metal pins B having the input leads P of the valve or lamp soldered to them.

It will be understood that such a capping operation demands, not only special equipment, but also the exercise of certain precautions, in particular as regards the choice of the paste, which 2 is solidified in a baking oven at a predetermined temperature and exerts a certain amount of compression on the glass wall of the bulb. Such compressive action is liable to involve risks of fracture if the degree of contraction or shrinkage of the paste be not suitably chosen.

The present invention has for its object to provide a simple method of capping which eliminates the aforementioned drawbacks by enabling the sealing of the cap on to the bulb to be avoided.

According to the invention, use is made of a. cap of insulating material provided with holes positioned in accordance with the spacing of the current leads of the base, or with a slightly different spacing: said leads are inserted in said holes, then a fusible metal or alloy is poured into said holes, thereby not only producing the electric contacts of thevalve or lamp elements, but also enabling the cap to be firmly fixed to the bulb without the use of any cement or paste. For the rest, bosses may be provided either on the cap, or on the base of the bulb, which bosses penetrate into recesses of corresponding shapes and dimensions, provided in the base or in the cap, thereby imparting to the whole arrangement sufficient strength to withstand twisting stresses.

Figure 3 shows, by way of example and without limitation as to the shape and the arrangement of the various elements, one construction according to the invention. In this figure, L represents the bulb of the lamp provided with its exhaust tube Q and with a recess E in its base; C represents the cap of insulating material provided with tapered holes 0 into which are passed the lead-in conductors P, a fusible metal or alloy Z being then poured into said holes 0 to provide the electric contacts for the internal elements of the lamp, and also to fix the cap to the bulb. The said cap is also provided with a boss A, penetrating into the recess E of the base, and with a protruding portion D serving to protect the exhaust tube Q. This same portion D serves also to guide the base relatively to the support socket when it is inserted therein in order to connect the tube to external circuits, the shape of said protruding portion being adapted to that of the said support.

When it is desired to use the above-described method for capping lamps or valves intended to be used horizontally, or oriented in any desired direction (as in the case of an incandescent lamp, for instance) the cap is so shaped that it keeps the lamp in its support.

Figures 4a and 4b show, by way of a nonway of metal parts M moulded into the capzand having the ends of the lead-in conductors soldered to them by means of the added alloy or metal Z. Alternatively, the contacts may be established simply by way of the added alloy or metal itself when the same is sufficiently adherent to the cap used.

Of course, the metal parts M and-also the" support S may be so shaped that they, form a screw or'a bayonet cap and socket.

I claim:

1. A vacuum tube comprising a glass stem, lead-in wires connected-to the electrodes of the tuhe, .sa-id wir'es traversing the stem andbei'ng cementedtherein, :a eap closely applied'to the stein and constituted of: insulating material, 'said c'a-p be-i-ng' provided with preferably outwardly tapered apertures, a head of fusible metal being fused. in saidaperturesytheends of the lead n wires issuing from the stem'being embedded ill the beadsthereby to retain the opposedsurfaces oft'he' stern' and base indireot mutual contact, the stem :and cap lbeing interlocked against mu tual rotation, the opposed surfaces of said stern andmap-bei-ngiprovided the one with hollowed out portions and the othenwith: complementary bosses closelvfitting into saidhollowedout portions.

":ZZJA vacuum tube comprising a glass stein, lead-inWires connected to the electrodes of the tube, said wires traversing thestem and being cemented therein, a'ca'p-clos'ely applied to the sternaand constitutedof insulating material, said cap "being provided with preferably outwardly tapered apertures, a bead of fusible metal being fuseddn-Said apertures, the endsof the lead in' wires'issuingfrom the stern-being embedded in the'be'ads thereby'to retain the opposed surfaces of the sterr'i'and basein direct mutual contact, the stem and cap being interlockedagainst-mutual rotation-the opposed surfaces of said stem and cap being-provided the one with hollowed out portions and the other with complementari bosses closely -fitting into said hollowed out por- U tions, an exhaust pip extendingfrom said stem surface, and a'dished central portion of said cap accommodating the exhaust pip.

4 3. A vacuum tube comprising a glass stem, lead-in wires connected to the electrodes of the tube, said wires traversing the stem and being cemented therein, a cap closely, applied to the stern and constituted of insulating material, said ...cap being provided with preferably outwardly tapered apertures, a bead of fusibIe alloy being [fused in said apertures, the ends of the lead-in wires issuing from the stem being embedded in the beads thereby to retain the opposed surfaces of the stem and base in direct mutual contact, the stem and cap being interlocked against mutual rotation, the opposed surfaces of said stem and cap being provided the one with hollowed out portions and the other with complementary bosses closely fitting into said hollowed out portions.

4. A vacuum tube comprising a glass stem, lead-in wires connected to the electrodes of the tube, said wires traversing the stem and being cemented therein, a cap closely applied to the stem and constituted of insulating material, said cap "being provided with preferably outwardly tapered apertures, 'a bead of fusible alloy being fused in said -apertures, the ends of the lead-in wiresiss'uing from the stem being embedded in the beads thereby to retain the opposed surfaces of the stem and base in direct mutual contact, the stem and cap being interlocked against' mutual rotation, the opposed surfaces of said stem and cap being provided the one with hollowed out portions and the other with complementary bosses closely'fitting into said hollowed out-portions, an exhaust pip extending from said-stem surface, and a dished central portion of said cap accommodating the exhaust pip.

ANDRE COMMIN.

appearances or an The following references are of record inthe fi1e-of-this patent:

1 UNITED STATES PATENTS 

